Hitachi EC12 Portable Electric 2hp Air Compressor, Oil Lubricated Logo
Posted on Feb 03, 2009
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Hitachi ec12 motor hums after drop in pressue

Hitachi ec12 pumps up pressure to normal but will not restart. just hum after drop in pressure. will eventually blow breaker.

  • 2 more comments 
  • bobnik Feb 05, 2009

    starts real slow and sound like it wants to pop breaker.... then runs fine until next start up!

  • Anonymous Mar 21, 2009

    If there is even 20lbs of pressure in the tank, the compressor won't completely fire up. I was told there is an adjustment somewher, but can't seem to figure it out.

  • Anonymous Jul 07, 2013

    Replace start valve part #160-615 located on the engine head

  • Anonymous Jul 07, 2013

    I had a Problem with my compressor, motor hummed after drop in pressure, it wouldn't start back up. I cut of a part of the plastic cover to reach the Start Valve, when the pressure starts to build up a pin from the center hole of the start valve pops out, and by my understanding when the motor shuts off the pin is supposed to pop back in, but it didn't. So I tapped the pin with a screw driver and the pin went back in the start valve. Then I released the pressure until 80 psi (i think it depends on the adjustment) and engine started back up no problem. But i have to tap it each time for it to start like its supposed to. I ordered a new Start Valve, it should work well. .

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  • Posted on Jul 07, 2013
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I have same problem on my Hitachi EC12
It seems Start Valve (part# 160-615) need to be replaced, located on engine head, so i ordered a new Start valve
I asked about my problem with my compressor on amazon.
here is the answer i got from Amazon

A fellow customer answered your question, "how works START VALVE (160-615) on Hitachi EC12 air compressor ?" about Hitachi EC12 14.5 amp...
Edward Fitzgibbon answered
"A start valve allows the air compressor to start without a load(no-load start). It releases the compressed air from the cylinder head.This feature uses less motor amperage in the starting process of the unit. Without this feature the compressor cylinder would be under pressure and the electric motor would under this additional strain would trip the circuit breaker."
you will find Start Valve on this website
http://www.ereplacementparts.com/hitachi-ec12-portable-electric-2hp-oil-lubricated-air-compressor-parts-c-7927_13217_13219.html

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  • Posted on Feb 08, 2009
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There should be a pressure switch adjustment under the cover of the switch remove the cover and reset.

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